Box Frequency , Subsonic Filter , and Low Pass Filter

[Alien Mantis]

The type of music you listen to makes a big difference.

If you optimize your bass for rap beats, it won't be optimized for rock, and vise versa.

A box tuned to 40hz is pretty low.
For me, bass below 40hz is something I "feel" more than I "hear".

I like bass optimized around 60-80hz.
I set my bass amp crossover at 100hz.
Subsonic filter would be 35hz, if I had one.
I listen to rock and metal.

My main 6 1/2" speakers are set with a high-pass filter at 125hz.
So they play nothing below that frequency.
My system is missing frequencies between 100 and 125hz.
I don't even notice.

I tried setting my bass amp filter at 80hz, but I lose a little mid-bass.
( The bass guitars )
So 100hz is best for my system.

My ported box "sounds" to me like it is tuned for around 65hz, although I am sure the actual tuning freq is probably a little lower.

The typical rule-of-thumb is: rap music = big ported box. rock = sealed box.
The type of sub and amp (power) is also important.

I'm no expert, but I do mess around with this stuff from time to time.
Just my $.02

YMMV